A wide variety of cleaning compositions for hard surfaces have been disclosed in the prior art. Most of these compositions are concerned only with performance, on a wide variety of stains and in a wide variety of conditions. And most hard surfaces are rather resistant to the point that it is generally not a concern that these surfaces may be permanently damaged by the cleaning composition.
However marble and lacquered surfaces are two types of surfaces which do require particular attention, when formulating cleaning compositions for their cleaning. Indeed, marble is mainly composed of calcium carbonate, and is therefore incompatible with cleaning compositions which would be acidic to neutral and/or which would comprise a builder. Indeed, acidity would "dissolve" marble, while the builder, whose function is specifically to bind ions which are present in water and dirt particles, would also bind the calcium in the marble, thereby turning the surface from very shiny to dull, as the introduced surface irregularities lower the reflectance of the surface. More surprisingly, we have found that most cleaning products formulated at neutral pH, containing builders and/or anionics, also damage marble. Thus the formulation of an alkaline, builder free composition would seem indicated in the present circumstances.
However, the formulation of an alkaline composition does not accommodate the cleaning of lacquered and painted surfaces, such as painted metal surfaces, or lacquered and painted wooden surfaces e.g. lacquered wooden floors. As used herein, lacquers are typically made out of polyurethanes or polyacrylates or mixtures of both, and paint is mainly pigmented polyacrylates, polyvinylacetates or alkydresins. Indeed such surfaces are permanently damaged by alkalinity. Specifically, alkalinity would destroy the lacquer and therefore give the lacquered surface the appearance of dullness or a colour change. Thus it would appear that formulating a cleaning composition which is suitable for cleaning both marble and lacquered surfaces is hindered by incompatible pH requirements.
Also, the absence of a builder, which is desirable for preserving the marble, is somewhat incompatible with a good performance for the cleaning of grease/particulate soil. Indeed, it has been observed that dirt comprises Ca2+, Mg2+ and/or metal ions which, in turn, most probably bind the charged ends of the fat molecules in grease, thereby forming a dirt-grease complex which is difficult to removal. The presence of a builder which binds the metal ions loosens the complex and therefore helps its removal.
Thus it is an object of the present invention to formulate a liquid composition which is suitable for the cleaning of both marble and painted and lacquered surfaces, and which provides good cleaning performance, in particular which performs well on grease removal.
In response to this object, we have formulated a liquid composition which comprises at least one surfactant, which is formulated at a mildly acidic to mildly alkaline pH , which comprises a builder, and positive divalent ions in amounts so as to saturate the builder in the composition.
Indeed, we have found that in the present compositions, the mildly acidic to neutral pH does damages neither marble nor lacquers. Also, the builder saturated with the positive divalent ions prevents the damage on marble, while it still displays its building action, as evidenced by improved grease cleaning performance.
Cleaning composition which are said to be for delicate surfaces are described in EP 511 091, CN 1055198 (title) and CN 10 32 360 (title).